networking, protocol (SPX) A transport layerprotocol built on top of IPX. SPX is used in Novell NetWare systems for communications in client/serverapplication programs, e.g. BTRIEVE (ISAM manager). SPX is not used for connections to the file server itself; this uses NCP. It has been extended as SPX-II. SPX/IPX perform equivalent functions to TCP/IP. (https://developer.novell.com/research/appnotes/1995/december/03/04.htm). [Better reference?] (1999-05-27)